In both DNA and RNA, heterocyclic base and phosphate ester linkages are at

Options

A. `C'_(5)` and `C'_(2)` respectively of the sugar molecule
B. `C'_(2)` and `C'_(5)` respectively of the sugar molecule
C. `C'_(1)` and `C'_(5)` respectively of the sugar molecule
D. `C'_(5)` and `C'_(1)` respectively of the sugar molecule

Answer

To answer the question regarding the positions of heterocyclic bases and phosphate ester linkages in both DNA and RNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Nucleotides**:
- Nucleotides are the building blocks of DNA and RNA. Each nucleotide consists of three components: a phosphate group, a sugar molecule (deoxyribose in DNA and ribose in RNA), and a nitrogenous base (heterocyclic base).

2. **Identify the Components**:
- The sugar molecule has five carbon atoms, typically numbered from 1' to 5'.
- The heterocyclic base is attached to the 1' carbon of the sugar.
- The phosphate group is attached to the 5' carbon of the sugar.

3. **Locate the Positions**:
- In the structure of a nucleotide:
- The heterocyclic base is linked to the sugar at the **1' (C1)** position.
- The phosphate group is linked to the sugar at the **5' (C5)** position.

4. **Conclusion**:
- Therefore, in both DNA and RNA, the heterocyclic base and phosphate ester linkages are at **C1 and C5** of the sugar molecule, respectively.

### Final Answer:
The heterocyclic base and phosphate ester linkages in both DNA and RNA are at **C1 and C5**, respectively.

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